LONDON — Authorities in northern England have charged a 24 year-old man with threatening to kill 200 people in a Facebook posting that caused thousands of Tennessee children to stay home from school. — More.

This sign was added in the student drop off and pickup area at my daughter’s school. It not only pertains to large vehicles such as delivery trucks, but also all family vehicles. I’ve asked Knox County Schools to see how many, if any, of their schools ban idling. I’ll update this when I hear back. The practice seems rather common but it’s mainly with school buses.

UPDATE: The always helpful Melissa Copelan, spokeswoman for the schools, passes along this information. Some of the schools are participating in idle-free zones.